5.2 Flashcards

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1
Q

cyclic photophosphorylation

A

light hits photostems
electrons are excited to a higher energy level and leave the photostem
the excited electrons pass along the etc releasing energy
the energy provides energy for chemiosmosis
H+ ions are actively pumped from low conc in stroma to high in thylakoid forming conc gradient
H+ ions diffuse back across the thyl.. into stroma via ATP synthase enzymes
movement of H+ cause ATP synthase to catalyse the production if ATP
electrons rejoin photosystem at end of electron transport chain in a cycle
ATP produced enters the light independent reaction

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2
Q

non-cyclic photophosphorylation

A

light energy hits photostem 2 in thylak..
two electrons gain energy- exited- higher
excited leave photostem and pass to etc
they are replaced by electrons from the photolysis of water
energy is released which allows chemiosmosis
H+ ions are actively pumped from low conc in stroma to high in thylakoid forming conc gradient
H+ ions diffuse back across the thyl.. into stroma via ATP synthase enzymes
movement of H+ cause ATP synthase to catalyse the production if ATP
at the end of etc electrons are passed from photostem 2 to 1
light energy hits photostem 1 exciting another pair of electrons which leave
then pass along etc
then combine with H+ ions from photolysis of water and NADP to form reduced NADP
reduced NADP and ATP passes to light independent reactions

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3
Q

light dependant

A

Thylakoids of chloroplast which contain chlorophyll
* Photons hit chlorophyll which becomes excited
(raised to a higher energy level)
* Two high energy electrons are emitted
* Electrons pass down ETC on thylakoid membrane
* ATP is synthesised by photophosphorylation
* Energy is used for photolysis (splitting of water) to
produce two electrons (replace those lost from
chlorophyll, protons and oxygen
* Electrons are used to reduce NADP to NADPH
* NADPH and ATP are used in the Light Independent
reaction.
* Oxygen is released into the atmosphere.
hydrogens build up in thylakanoids

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4
Q

light-independent

A

calvin benson cycle
atp and reducted natp used
co2 fixed
co2 converted to glucose
occurs in stroma of chloroplasts

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5
Q

calvin benson cycle

A

co2 diffuse into stroma
ribulose biphosphate (RuBP) binds to and carbon fixes CO2 5c
catalysed by the enzyme rubisco
-highly unstable 6c compound is formed which immediately splits into two molecules of 3c glycerate 3phospate (gp)
ATP and NADPH are used to reduce gp into glyceraldehyde 3 phosphate (galp)
some is used to make carbohydrate but most makes rubp so cycle can continue
for every glucose produced 5 molecules of rubp are made

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6
Q

autotroph

A

organism which makes complex organic compounds from simple inorganic compounds

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7
Q

heterotroph

A

organism that obtains complex organic compounds by feeding on other organisms dead remains

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8
Q

photosynthesis

A

converts light energy into chemical
light energy is used to split bonds in water
O2 released as a waste product
hydrogen combined with carbon dioxide to form glucose

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9
Q

photosynthetic pigments

A

chlorophyll a
chlorophyll b
-similar action and absrobstion spec
carotenoids

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10
Q

absorbtion spectrum

A

absorption of light compared to wavelength

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11
Q

action spectrum

A

rate of photosyntehsis against wavelength

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12
Q

rf

A

distance of solute (colour) / distance of solvent

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13
Q

rate limiting factors of photosynthesis

A

light - affects the amount of chlorophyll excited
co2 - calvin cycle
temp - controlled enzymes

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14
Q

importance of thylakoid membranes

A

contains photostems so light can be absorbed
contains carrier proteins so hydrogen pumped into thylakoid space
contains atp synthase so hydrogen can pass through
membranes form a barrier so H+ ions can accumulate
membranes are the site of chemiosmosis

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15
Q

units for photosynthesis

A

umol - galp produced
m^-2 - area of leaf
sec^-1- in one second

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16
Q

light intensity affect on rate of photosyntehsis

A

increase
stomata open wider
more gas exchange
faster Calvin benson cycle
evens off when co2 conc becomes limiting factor

17
Q

wider stomata

A

increase yield
more gas exchange
faster rate of photosynthesis
more glucose produced
faster transpiration streams
more mg to form chlorophyll